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Gain (laser)
In laser physics, gain or amplification is a process where the medium transfers part of its energy to the emitted electromagnetic radiation, resulting in an increase in optical power. This is the basic principle of all lasers. Quantitatively, ''gain'' is a measure of the ability of a laser medium to increase optical power. However, overall a laser consumes energy. Definition The gain can be defined as the derivative of logarithm of power ~P~ as it passes through the medium. The factor by which an input beam is amplified by a medium is called the gain and is represented by G. :G = \frac\ln(P)=\frac where ~z~ is the coordinate in the direction of propagation. This equation neglects the effects of the transversal profile of the beam. In the quasi-monochromatic paraxial approximation, the gain can be taken into account with the following equation : 2ik\frac= \Delta_E + 2 \nu E + i G E, where ~\nu~ is variation of index of refraction (Which is supposed to be small), ~E~ is complex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laser Physics
Laser science or laser physics is a branch of optics that describes the theory and practice of lasers. Laser science is principally concerned with quantum electronics, laser construction, optical cavity design, the physics of producing a population inversion in laser media, and the temporal evolution of the light field in the laser. It is also concerned with the physics of laser beam propagation, particularly the physics of Gaussian beams, with laser applications, and with associated fields such as nonlinear optics and quantum optics. History Laser science predates the invention of the laser itself. Albert Einstein created the foundations for the laser and maser in 1917, via a paper in which he re-derived Max Planck’s law of radiation using a formalism based on probability coefficients ( Einstein coefficients) for the absorption, spontaneous emission, and stimulated emission of electromagnetic radiation. The existence of stimulated emission was confirmed in 1928 b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Passive Elements
Passive may refer to: * Passive voice, a grammatical voice common in many languages, see also Pseudopassive * Passive language, a language from which an interpreter works * Passivity (behavior), the condition of submitting to the influence of one's superior * Passive-aggressive behavior, resistance to following through with expectations in interpersonal or occupational situations * Passive income, income resulting from cash flow received on a regular basis * Passive immunity, the transfer of active humoral immunity * Passive experience, observation lacking reciprocal interaction; and wrought with delusion of control. Science and technology * Passivation (chemistry), process of making a material "passive" in relation to another material prior to using the materials together * Passivity (engineering) a property of engineering systems, particularly in analog electronics and control systems * Passive solar building design, which uses (or avoids) sunlight as an energy source without a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Effective Cross-sections
The McCumber relation (or McCumber theory) is a relationship between the effective cross-sections of absorption and emission of light in the physics of solid-state lasers.D.E.McCumber. Einstein relations connecting broadband emission and absorption spectra. PRB 136 (4A), 954–957 (1964)P.C.Becker, N.A.Olson, J.R.Simpson. ''Erbium-doped fiber amplifiers: fundamentals and theory'' (Academic, 1999). It is named after Dean McCumber, who proposed the relationship in 1964. Definition Let \sigma_(\omega) be the effective absorption cross-section \sigma_(\omega) be effective emission cross-sections at frequency \omega, and let ~T~ be the effective temperature of the medium. The McCumber relation is :(1) \frac\exp\!\left( \frac\right) =\left(\frac\right)_T =\exp\!\left( \frac\right) where \left(\frac\right)_T is thermal steady-state ratio of populations; frequency \omega_ is called "zero-line" frequency; \hbar is the Planck constant and k_ is the Boltzmann constant. Note that t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Disk Laser
A disk laser or active mirror (Fig.1) is a type of diode pumped solid-state laser characterized by a heat sink and laser output that are realized on opposite sides of a thin layer of active gain medium. Despite their name, disk lasers do not have to be circular; other shapes have also been tried. The thickness of the disk is considerably smaller than the laser beam diameter. Initially, this laser cavity configuration had been proposed and realized experimentally for thin slice semiconductor lasers. The disk laser concepts allow very high average and peak powers due to its large area, leading to moderate power densities on the active material. Active mirrors and disk lasers Initially, disk lasers were called ''active mirrors'', because the gain medium of a disk laser is essentially an optical mirror with reflection coefficient greater than unity. An active mirror is a thin disk-shaped double-pass optical amplifier. The first active mirrors were developed in the Laboratory for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ambiguity
Ambiguity is the type of meaning (linguistics), meaning in which a phrase, statement, or resolution is not explicitly defined, making for several interpretations; others describe it as a concept or statement that has no real reference. A common aspect of ambiguity is uncertainty. It is thus an Attribute grammar, attribute of any idea or statement whose intention, intended meaning cannot be definitively resolved, according to a rule or process with a finite number of steps. (The prefix ''wikt:ambi-#Prefix, ambi-'' reflects the idea of "2 (number), two", as in "two meanings"). The concept of ambiguity is generally contrasted with vagueness. In ambiguity, specific and distinct interpretations are permitted (although some may not be immediately obvious), whereas with vague information it is difficult to form any interpretation at the desired level of specificity. Linguistic forms Lexical ambiguity is contrasted with semantic ambiguity. The former represents a choice between a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Absorption Coefficient
The linear attenuation coefficient, attenuation coefficient, or narrow-beam attenuation coefficient characterizes how easily a volume of material can be penetrated by a beam of light, sound, particles, or other energy or matter. A coefficient value that is large represents a beam becoming 'attenuated' as it passes through a given medium, while a small value represents that the medium had little effect on loss. The (derived) SI unit of attenuation coefficient is the reciprocal metre (m−1). Extinction coefficient is another term for this quantity, often used in meteorology and climatology. Most commonly, the quantity measures the exponential decay of intensity, that is, the value of downward ''e''-folding distance of the original intensity as the energy of the intensity passes through a unit (''e.g.'' one meter) thickness of material, so that an attenuation coefficient of 1 m−1 means that after passing through 1 metre, the radiation will be reduced by a factor of '' e'', and fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radiophysics
Radiophysics (also modern writing radio physics) is a branch of physics focused on the theoretical and experimental study of certain kinds of radiation, its emission, propagation and interaction with matter. The term is used in the following major meanings: *study of radio waves (the original area of research) *study of radiation used in radiology in ''Medcyclopaedia'' (archived from the original), online version of the '' Encyclopaedia of Medical Imaging'' *study of other ranges of the spectrum of |
Gain Medium
The active laser medium (also called a gain medium or lasing medium) is the source of optical gain within a laser. The gain results from the stimulated emission of photons through electronic or molecular transitions to a lower energy state from a higher energy state previously populated by a pump source. Examples of active laser media include: * Certain crystals, typically doped with rare-earth ions (e.g. neodymium, ytterbium, or erbium) or transition metal ions (titanium or chromium); most often yttrium aluminium garnet ( Y3 Al5 O12), yttrium orthovanadate (YVO4), or sapphire (Al2O3); and not often caesium cadmium bromide ( Cs Cd Br3) (solid-state lasers) * Glasses, e.g. silicate or phosphate glasses, doped with laser-active ions; * Gases, e.g. mixtures of helium and neon (HeNe), nitrogen, argon, krypton, carbon monoxide, carbon dioxide, or metal vapors; ( gas lasers) * Semiconductors, e.g. gallium arsenide (GaAs), indium gallium arsenide (InGaAs), or gallium nitride (GaN ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnification Coefficient
Magnification is the process of enlarging the apparent size, not physical size, of something. This enlargement is quantified by a size ratio called optical magnification. When this number is less than one, it refers to a reduction in size, sometimes called ''de-magnification''. Typically, magnification is related to scaling up visuals or images to be able to see more detail, increasing resolution, using microscope, printing techniques, or digital processing. In all cases, the magnification of the image does not change the perspective of the image. Examples of magnification Some optical instruments provide visual aid by magnifying small or distant subjects. * A magnifying glass, which uses a positive (convex) lens to make things look bigger by allowing the user to hold them closer to their eye. * A telescope, which uses its large objective lens or primary mirror to create an image of a distant object and then allows the user to examine the image closely with a smaller eyepi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electromagnetic Radiation
In physics, electromagnetic radiation (EMR) is a self-propagating wave of the electromagnetic field that carries momentum and radiant energy through space. It encompasses a broad spectrum, classified by frequency or its inverse, wavelength, ranging from radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. All forms of EMR travel at the speed of light in a vacuum and exhibit wave–particle duality, behaving both as waves and as discrete particles called photons. Electromagnetic radiation is produced by accelerating charged particles such as from the Sun and other celestial bodies or artificially generated for various applications. Its interaction with matter depends on wavelength, influencing its uses in communication, medicine, industry, and scientific research. Radio waves enable broadcasting and wireless communication, infrared is used in thermal imaging, visible light is essential for vision, and higher-energy radiation, such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Round-trip Gain
Round-trip gain refers to the laser physics, and laser cavity, laser cavities (or laser resonators). It is gain, integrated along a ray, which makes a round-trip in the cavity. At the continuous-wave operation, the round-trip gain exactly compensates both the output coupling of the cavity and its background loss. Round-trip gain in geometric optics Generally, the Round-trip gain may depend on the frequency, on the position and tilt of the ray, and even on the polarization of light. Usually, we may assume that at some moment of time, at reasonable frequency of operation, the gain (lasers), gain ~G(x,y,z)~ is function of the Cartesian coordinates ~x~, ~y~, and ~z~. Then, assuming that the geometrical optics is applicable the round-trip gain ~g~ can be expressed as follows: :~g=\int G(x(a),y(a),z(a))~a~, where ~a~ is path along the ray, parametrized with functions ~x(a)~, ~y(a)~, ~z(a)~; the integration is performed along the whole ray, which is supposed to form the closed loop. In s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laser Pumping
Laser pumping is the act of energy transfer from an external source into the gain medium of a laser. The energy is absorbed in the medium, producing excited states in its atoms. When for a period of time the number of particles in one excited state exceeds the number of particles in the ground state or a less-excited state, population inversion is achieved. In this condition, the mechanism of stimulated emission can take place and the medium can act as a laser or an optical amplifier. The pump power must be higher than the lasing threshold of the laser. The pump energy is usually provided in the form of light or electric current, but more exotic sources have been used, such as Chemical reaction, chemical or nuclear reactions. Optical pumping Pumping cavities A laser pumped with an arc lamp or a flashlamp is usually pumped through the lateral wall of the lasing medium, which is often in the form of a crystal rod containing a metallic impurity or a glass tube containing a liquid d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
